Preheat oven to 350º F. Grease and flour 13 x 9-inch baking pan.

Melt 3/4 cup morsels in a small, microwave-safe bowl on HIGH (100%) power for 45 seconds; stir. If necessary, microwave at additional 10- to 15-second intervals, stirring just until smooth. Add coffee granules and ¼ cup evaporated milk; stir well until coffee is completely dissolved. Set aside.

Combine nuts, remaining ¼ cup morsels, 1/3 cup sugar and 2 tablespoons butter in medium bowl until crumbly. Set aside.

Combine flour, baking soda, salt and baking powder in medium bowl. Beat remaining 1 1/2 cups sugar and remaining 6 tablespoons butter in large mixer bowl until well blended. Beat in sour cream, eggs, remaining 3/4 cup evaporated milk and vanilla extract until blended. Gradually beat in flour mixture. Remove 1 cup of batter and set aside. Stir chocolate mixture into remaining batter. Pour chocolate batter into prepared pan.

Drop tablespoons of reserved batter randomly over chocolate batter. Swirl mixture with knife for marbled effect. Sprinkle nut mixture over top.

Bake for 38 to 40 minutes or until wooden pick inserted in center comes out clean. Cool completely in pan on wire rack.